Automatic pressure measuring and indicating system



Sept. 8, 1953 A. H. DlcKlNsoN. 2,651,204

AUTOMATIC PRESSURE MEASURING AND INDICATING SYSTEM Filed'uareh 9, 1950 5 sheets-sheet 1 INVEN'roR Af 7710/' DKK/0600 BY r ATTORNEY Sept. s, 1953 A; H. .DlcKlNsoN 2,651,204- AUToMATIc PRESSURE MEASUR Filed March 9, 1950 ING AND INDICATING SYSTEM 5 Sheets-Sheet 2 lNvENToR Arr/wr H. wdr/05M BY A M ATTORNEY Sept. 8, 1953 AUTOMATIC PRESSURE MEASURING Filed March 9, 1950 AND INDICATING SYSTEM 5 Sheets-Sheet 5 I l fw I HUND/afm nmz/mw mv wam/vm BY i 4 ATTORNEY4 A. H. DlcKlNsoN 2,651,204

Sept. 8, 1953 A. H. DICKINSON AUTOMATIC PRESSURE MEASURING AND INDICATING SYSTEM Filed 'March 9, 195o y 5 Sheets-Sheet @fafa/:mm af me Aff/0d E [n 05 '1 #fic/05650045 l E 5f |NvENKToR Aff/fur H. alarma/z l'sY ATTORNEY Patented Sept. 8,l 1953 UNITED STATES PATENT OFFICE AUTOMATIC PRESSURE MEASURIN G ANI) INDICATIN G SYSTEM eenwich, Conn., assignor slness Machines Corporaa corporation of NeW Application March 9, 1950, Serial No. 148,543 1 Claim. (Cl. 73-398) This invention relates generally to an electronic pressure digital value indicating system.

The principal object of the invention is to provide an automatic electronic pressure digital value indicating system.

Another object of the invention is to provide an automatic pressure indicating system which registers a digital value of pressure in an elec- 'period and indicates said ond period.

Other objects of the invention will be pointed out in the following description and claim and ilof the complete Fig. 2.

Fig. 9 is a graph showing the relationship between the period of a multivibrator measured in manometer of Fig. 3.

Fig. 10 is a timing diagram Referring to Fig. 2 there is illustrated the details of a pressure actuated variable capacitor The metallic acts as a plate of the coupling condenser between triode V2 which may be a 6SN7 and the control grid of a triode VI which may also be a 6SN7.

The plate of Vl is coupled to the control grid of V2 through a fixed capacitor C1 of 120 micromicrofarad, for example. The cathode of each of the tubes V1 and V2 is connected to the negative side of the main source of power line i1, while the anodes of each of the triodes Vl and V2 are respectively connected through the resistors R1 and R2 each of 0.0027 megohm, for example, to the line 18, the main positive source of potential of approximately 105 volts. grid resistors R3 and R4 each of 0.5 megohm are conne-cted between the respective grids of the GSN'I triodes V1 and V2 and the line il. With the capacitance of C1 remaining constant, as the height of the mercury column and thus the capacitance ci the manometer capacitor varies in proportion to the pressure, the period of the multivibrator varies linearly in accordance with the change in -coupling capacitance as shown in Fig. 7.

The multivibrator MV2 (Figs. 1 and 4) is .of a well known type having a iixed frequency output, which is continuously applied to the suppressor grid oi a normally blocked pentode V3 of the gate circuit through C2 and resistor R'S. The anode and screen grid of V3 are connected to the high side of the main power supply through the respective resistors Rl and RB, its control grid is coupled through the resistor R to the gate trigger circuit via lines 18 and 19, while its cathode is connected to the low side of the main power supply.

The trigger of the gate circuit comprises a cross-coupled triode V4 and pentode V5. The screen grid of pentode V5 is coupled tc the grid of triode V4 through an impedance network comprising a capacitor C3 and a resistor R10 while the anode of V4 is coupled to the grid oi V5 through an impedance network comprising a capacitor C4 and resistor R1 1. The control grids of each of the tubes V4 and V5 are connected respectively through resistors R12 and R13 to the negative bias power supply while each o the cathodes of V4 and V5 is connected to the low side of the main power supply. The junction of the resistors R11 and R13 is coupled through capacitors C5 and -CB to the junction of the resistors R and R12. The trigger has two stable conditions in one of which triode V4 is conducting and pentode V5 is non-conducting the second condition pentode V5 conducts and triode V4 is non-conducting. In the normal stable condition of the trigger, V4 is conducting, and this is called the ofi or blocking condition.

Thus it is to .be noted that in the `operation of the gate circuit when the trigger is off (V4 conducting and V5 non-conducting), the grid bias of pentode V3 is sufficiently negative to render gate V3 non-conductive thus blocking the output of the fixed frequency multivibrator MV2 from being applied to the result counter (Fig. l). When the trigger is on (V4 non-conducting), the grid bias of V3 is zero thereby unblocking this tube .so that the output from the multivibrator MVZ is applied to the result counter. The operation of the gate trigger is determined by a standard electronic counter which will now be described.

The varying output from the manometer controlled multivibrator MV1 is continuously applied by means oi a conductor 29 (Figs. 4, 5 and 6) to the units order of a standard -counter which counts the pulses from MV1. This standard electronic counter, as shown in Fig. 6, comprises The the resistor R5, capacitor while in 'number of pulses six orders, namely, units, tens, hundreds, thousands, ten thousands and hundred thousands orders, respectively. Each order (see Hundreds, Fig. 6) comprises four trigger circuits all similar. As shown, trigger stages #1, #2, #4 and cording to the binary notation, the number assigned to a particular stage representing the necessary to shift that particular stage.

The #l trigger stage comprises a pair of triodes V6 and V1 shown as having a common cathode connected to ground. The anode of V6 is coupled to the control grid of V1 through an impedance network comprising a resistor R14 and a capacitor C1 of Vl is coupled to pedance network comprising a res1stor R15 and a capacitor C8. The resistors nected between the respective grids of the triodes V5 and Vl and the bias supply. Anode resistors R18 and R15 of Vl and the single anode resistor R20 of V0 are connected between the positive side of the power supply and the respective iinpedance network associated therewith, while the control grids of the triodes are coupled together through capacitors C0 and C10. The output from the #8 stage .of the tens order is applied by means of a line 20 to the #1 trigger of this hundreds order through the capacitors C9 and C10. The output of the #1 trigger of the hundreds order is coupled to the #2 trigger of the same order (shown at the eXtreme left in Fig. 6) by means of a line 21 extending from the junction oi resistors R18 and R19 of'tube Vl of the #1 trigger to the capacitors C9 and C10 of the #2 trigger. The #2 trigger which is identical in design with the #1 trigger is coupled to the #4 trigger through the respective capacitors C9 and C10 to the #4 stage, The output of the #4 stage is applied to one side only of the #8 stage through a capacitor C11 while the output of the #8 stage is applied to the #1 stage, oi the next higher (thousands) order, by means of a line 22.

For the iirst nine pulses applied to the hundreds order, the triggers operate in straight binary. On the tenth pulse, however, there is an automatic forced resetting of the trigger circuits to an original or zero condition due to the coupling of the plate circuit of V1 of the #l trigger via line 21 and capacitor C12 to the grid of V13 of the #8 trigger and via the circuit from resistor R200, of the #8 trigger via line 31 and capacitor C14 to the grid of triode V8 of the #2 trigger, which returns the complete order to the original zero condition in a well known manner thereby converting operation of the counters from a binary to a tens notational basis.

A reset control switch T800 is inserted between line 26 leading from the control grid of V10 (Fig. 4) and line 21 connected to the input to the #8 stage of the hundreds order (Fig. 6) while a switch T1000 is inserted between line 28 leading from the control grid oi pentode V5 of Fig. 4 and the output of the #B stage (Fig. 6) of the hundreds order. These switches T1000 and T800 when in a closed position determine, respectively, the extent of a complete cycle and the time of resetting during alternate cycles, If it is desired to increase the extent of a complete cycle then any one of the switches T10,000 to T1,000,000 may be used along with the respective resetting switches T8000 to T800,000.

The result counter shown in Fig. 5 with the is employed to Y is connected through a resistor I9 to the junction of resistors RII and RI3 of the gate trigger while the control grid of VI6 is connected er associated therewith.

For the purpose of indicating the condition of each stage of the result counter, a resistor R26 (Fig. and neon lights LI change in the height of the mercury. Since the f6 manometer capacitor pling capacitors of the multivibrator MV I (Fig.

umn and thus also, the pressure.

The variable output from the multivibrator MVI 1s applied via l1ne 29 the #I -0- to -799-, the #8 trigger (Fig. 6) in the hundreds order is ein potential of the associated cuit thus initially resetting the result counter to zero.

After the result counter from the manometer controlled multivibrator when the count passes .from -999- negative pulse is applied to triode V4 of the gate trigger by means of the now closed switch TIOIJO (Fig. 6) and the line 28 (Figs. 6, 5 and 4) to condenser C6 whereby the gate trigger is turned on thus initiating a measuring cycle, as shown at 0 time on the timing diagram of Fig. 10. When the gate trigger is thus turned on, the gate pentode V3 (Fig. 4) is unblocked so that the output from the fixed frequency multivibrator MV2 is applied via line 23 to the #I trigger of the result counter (Fig. 5). During the next count of -1000- pulses by the standard counter, the result counter counts the output from this multivibrator MV2. After this second count of -1000- lhas been counted by the TI000 and the line 28 (Figs. 6, 5 and 4) to both sides of the gate trigger through the capacitors C5 and C6 flipping it off Thus the gate trigger is ipped alternately on and oil after each successive count of -1000- by the standard counter. After the measuring cycle is terminated, at the end of this second count of -1000-, the digital indication appearing in the result counter is a digital value a linear function of the height of the mercury column and thus of the pressure, all as detected by the manometer capacitor. After a read count of -800-, as Shown in Fig. l0, the result counter is again reset to prepare for the indication of another pressure measurement. Thus it is to be noted that each measuring cycle count is followed by an equal count which is employed for the dual purpose of manifesting the results, for approximately .8 of

Lthis count, Aand yresetti-ieig the result counter during ,therema'nder of this count (Fig. 10).

,f VDuring a measuring cycle there is no unwanted v;iesetti-ng of the result counter when the #3 trigger of the hundreds order of the standard ,counter is turned 'on. This is due to the 'fact r.that when the zgate trigger is on, the grid of V15 is maintained at zero bias thus producing a very substantial drop across R23. Thus when the #8 trigger of the hundreds order of the standard counter is tur-ned onf during a measuring cycle, the voltage drop across the resistor R23 is not `reduced to a magnitude sufcient to cause an V.unwanted resetting.

While there have been shown and described and pointed out the fundamental novel features of the vinvent-ion as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form. and details `cf the device illustrated and in its operation may vbe :made by those skilled in the art, Without departing from the spirit of the invention. It is the intention, therefore, to be limited onlly as indicated by the scope of the following claim.

What is claimed is:

1n .an automatic pressure measuring and indicating system comprising a pressure responsive variable capacitor, said capacitor comprising a 'glass tube manometer which further comprises a cylindrical glass member having a metallic coating `on the outer side thereof, a column of -mercury contained within said member, said mei-talliic vcoating and said column of mercury each forming a plate of said capacitor, the capacitance 'of said capacitor varying with a change in height 'of said mercury which varies linearly with pressure, a first multivibrator circuit, .means connectuing said capacitor in said circuit whereby the period of said circuit varies linearly with respect `to said pressure, a first electronic counter coupled to said circuit, a, second multivibrator circuit having a nxed frequency output, a second electronic counter, blocking means preventing the output of said second circuit from being applied to said second counter, said first counter being coupled to said blocking means, the output of said first circuit being continuously applied -to said first counter whereby said first counter cyclically and automatically unblocks and blocks said blocking means at equal counts, said second counter having entered therein the output from said second multivibrator Whenever -said blocking means becomes unblocked, said second counter manifesting said pressure by a digital representation, means automatically resetting said second counter after said manifesting, and means to prevent the unwanted resetting of said second counter during the count when said second circuit is unblocked.

ARTHUR H. DICKINSON.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES German Publication, Zeitschrift fur Electrocheme, vol. 35, No. fi, 1929, Article by Simon et al., pages 162-164. 

